U.S. patent application number 10/751774 was filed with the patent office on 2004-08-26 for method of retrofitting a decanting centrifuge.
Invention is credited to Hensley, Gary L., Hilpert, Lee.
Application Number | 20040167005 10/751774 |
Document ID | / |
Family ID | 32655717 |
Filed Date | 2004-08-26 |
United States Patent
Application |
20040167005 |
Kind Code |
A1 |
Hensley, Gary L. ; et
al. |
August 26, 2004 |
Method of retrofitting a decanting centrifuge
Abstract
A method of retrofitting a centrifuge comprises disassembling a
known centrifuge and replacing the conical beach section with a
shorter beach section, i.e. a beach section having a greater slope.
The screw conveyor is replaced with another screw conveyor having
outlet nozzles adapted to impart rotational movement to the inlet
feed.
Inventors: |
Hensley, Gary L.; (Kingwood,
TX) ; Hilpert, Lee; (Livingston, TX) |
Correspondence
Address: |
TIM COOK
P.O. BOX 10107
LIBERTY
TX
77575
US
|
Family ID: |
32655717 |
Appl. No.: |
10/751774 |
Filed: |
January 5, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60438650 |
Jan 8, 2003 |
|
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Current U.S.
Class: |
494/53 |
Current CPC
Class: |
B04B 1/20 20130101 |
Class at
Publication: |
494/053 |
International
Class: |
B04B 001/20 |
Claims
We claim:
1. A method of retrofitting a decanting centrifuge, comprising the
steps of: a. replacing a bowl section of the centrifuge outer body
with a longer bowl section; b. replacing a conical section of the
centrifuge outer body with a conical section defining a greater
slope angle; and c. replacing a screw conveyor of the centrifuge
with a screw conveyor having nozzles therein adapted to impart
rotation movement to feed liquid.
2. The method of claim 1, wherein the centrifuge is supported on a
pair of spaced apart pedestals.
3. A method of retrofitting a decanting centrifuge, comprising the
steps of: a. adding a segment of a bowl section of the centrifuge
outer body, thereby making the bowl section longer; b. replacing a
conical section of the centrifuge outer body with a shorter conical
section, wherein the combined length of the added segment of the
bowl section and the shorter conical section is substantially the
same as the replaced conical section; and c. replacing a screw
conveyor of the centrifuge with a screw conveyor having means
therein adapted to impart rotation movement to a slurry input to
the centrifuge.
4. The method of claim 3, wherein the centrifuge is supported on a
pair of spaced apart pedestals.
5. The method of claim 3, wherein the means to impart rotation
movement to feed liquid comprises a plurality of nozzles.
Description
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. No. 60/438,650 filed Jan. 8, 2003.
FIELD OF THE INVENTION
[0002] The present invention relates generally to the field of
decanting centrifugal separators, and, more particularly, to a
method of retrofitting a decanting centrifuge to extend the useful
life of such a centrifuge while substantially improving its
performance.
BACKGROUND OF THE INVENTION
[0003] A decanting centrifuge is commonly used for separating solid
matter from a solids-laden liquid. For example, drilling mud with
solids entrained therein must be effectively cleaned so that the
drilling mud can be recycled. For another example, many
manufacturing and food processing systems use vast quantities of
water. In such systems, the water picks up solid waste matter which
must be removed from the water before it can be discharged, whether
it is into the environment or into storage. Decanter centrifuges
have proved to be effective and efficient in carrying out this
function of removing the solids from the recyclable liquid.
[0004] Generally, a decanter centrifuge comprises a cylindrical or
frustoconical bowl rotating in one direction and at a particular
although variable speed, and a screw conveyor rotating in the same
direction but at a different speed. The difference in the speeds of
the bowl and the screw conveyor is commonly known in the art as the
differential speed.
[0005] In a well known decanting centrifuge structure, liquid which
is to be clarified enters an inlet to the centrifuge where it is
brought up to rotational speed around the interior surface of the
bowl. Heavier elements, i.e. solids, are brought to the interior
surface of the bowl by centrifugal force (furthest from the axis of
rotation), while lighter elements, i.e. water or drilling fluid,
remains closer to the axis of rotation of the centrifuge. The screw
conveyor, rotating at a speed slightly slower than that of the
bowl, conveys the solids toward a beach in a conical portion of the
bowl.
[0006] No matter how well a piece of machinery is built, eventually
it will wear out. Within a limited number of hours of high speed
operation, a centrifuge likewise will require maintenance and
eventually will have to be replaced because of worn parts. However,
even with much of a centrifuge at the end of its useful life, major
and costly portions of the centrifuge have substantial useful life
remaining. This means that a large, expensive piece of machinery is
often scrapped because only part of the machine is worn out.
[0007] Also, with improvements in technology, some machinery is
replaced simply because, although major portions of the machines
have useful lifetime left in them, when major overhaul is called
for, it makes good economic sense to upgrade the machinery. Such
full scale machinery replacement is often a major expenditure and
is not undertaken lightly.
[0008] Thus, there remains a need for a method of retrofitting a
centrifuge to extend the useful lifetime of the machine, while
simultaneously upgrading the performance of the machine.
SUMMARY OF THE INVENTION
[0009] The present invention addresses this need in the art by
providing a method of retrofitting a known centrifuge. The known
centrifuge includes a bowl formed of tandem sections and this
feature is used to advantage in the method of the present invention
to alter the configuration of the beach. This step in the method
requires modification to the bowl and screw conveyor, and this
modification must be accomplished within the constraint of a
longitudinal distance between pedestals on which the existing
machine is mounted.
[0010] The known centrifuge further includes a liquid inlet volume
within the screw conveyor which simply allows liquid friction to
bring the inlet liquid up to rotational speed of the bowl. This
feature of the known centrifuge is improved by providing a series
of radially oriented nozzles to impart rotational speed to the
incoming, solids-laden liquid.
[0011] These and other features and advantages of this invention
will be readily apparent to those skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] So that the manner in which the above recited features,
advantages and objects of the present invention are attained and
can be understood in detail, more particular description of the
invention, briefly summarized above, may be had by reference to
embodiments thereof which are illustrated in the appended
drawings.
[0013] FIG. 1 is a side section view of known decanting centrifuge
which is retrofitted and upgraded in carrying out the present
invention.
[0014] FIG. 2 is a side section view of the decanting centrifuge
after retrofit.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0015] FIG. 1 depicts a decanting centrifuge 10 which is to be
retrofitted by the method of the present invention. The centrifuge
10 comprises an outer body 12 which includes a bowl section 14 and
a conical section 16, joined together at a flanged joint 18. The
bowl section defines a slope angle of a. In practice, a plurality
of bowl sections 14 are provided, thereby enabling a bowl section
of a selectable length.
[0016] Enclosed within the outer body 12 is a screw conveyor 20,
coaxial with the outer body for rotation therein. The outer radial
profile of the screw conveyor 20 is in close proximity with the
inner surface of the outer body, both the bowl section and the
conical section, to convey solids toward the right as viewed in
FIG. 1, and out through a solids discharge 22. Liquids are
discharged through a liquids discharge port 24.
[0017] The centrifuge is supported on the solids end by a solids
end pillow block 26 and on the liquids end by a liquids end pillow
block 28. The pillow block 26 is supported on a pedestal 30 and the
pillow block 28 is supported on a pedestal 32, shown in FIG. 2. A
drive pulley 34 couples the centrifuge 10 to a prime mover (not
shown), which drives both the outer body 12 and the screw conveyor.
The difference in rotational speed between the outer body 12 and
the screw conveyor is provided by a transmission (not shown),
coupled to the machine at a gear flange 36 in a manner well known
in the art.
[0018] The left hand end of the centrifuge is closed off with a
liquids hub 38 and at the right hand end with a solids hub 40. An
inlet line 42 penetrates the solids hub 40 to introduce a solids
laden slurry into the centrifuge 10. The solids laden slurry passes
from the inlet line 42 into an inlet plenum 44, where it is forced
radially outwardly by the flow of more liquid behind it and in part
by fluid friction. Note that no structural member of the centrifuge
in the inlet plenum imparts rotational movement to the slurry to be
clarified. At this point, once the liquid is caught up in the screw
conveyor, rotational movement is imparted, and heavier solids are
moved by centrifugal force to the interior surface of the outer
body, and lighter liquids settle on top of the solids. The screw
conveyor moves the solids to the right to the conical section,
which defines the beach, while liquids are discharged to the
left.
[0019] The structure of the centrifuge 10 just described was
designed for a specific throughput of solids laden liquid, and has
proven to be successful for certain applications. In fact, many
such machines are currently installed and operating in industry.
However, many have reached the normal end of their life cycle, and
machines having superior performance are now available. So, even
though such machines have value, as they approach overhaul they are
being replaced. What is really needed is a method of retrofitting
such machines to improve their capability, while salvaging the
expensive portions of the machines still having substantial working
life remaining. The present invention provides such a method.
[0020] FIG. 2 depicts a centrifuge 50 after retrofit in accordance
with the present invention, having completed a retrofit of the
centrifuge 10 of FIG. 1. In FIG. 2, like components are given like
numerals.
[0021] The centrifuge 50 includes an outer body 52, comprising a
bowl section 54 and a conical section 56. Note that the conical
section 56 defines a much shorter axial length, and therefore also
defines a slope .beta., which is greater than the slope .alpha., of
the centrifuge 10. Note also that the screw conveyor 20 has been
replaced with a screw conveyor 58. The screw conveyor 58 defines a
longer axial length and a shorter frustoconical portion to conform
to the interior surface of the outer body. Also, the screw conveyor
20 defines an inlet line 60, which directs the inlet feed of solids
laden liquid into an inlet plenum 62. The inlet plenum 62 comprises
only the extreme end of the cylindrical portion of the screw
conveyor, and is blocked off from the remainder of the cylindrical
portion by a wall 65. The liquid entering the inlet plenum 62 is
forced out through nozzles 64, which also impart rotational motion
to the feed liquid as it enters the region between the outer body
and the screw conveyor.
[0022] While the bowl section 14 of the centrifuge depicted in FIG.
1 comprises a single section, the section may be formed of discrete
section portions coupled together at flanges 19, like the flange
coupling 18. In fact, the bowl section commonly includes three such
sections. However, in carrying out the retrofit method of the
invention, an additional cylindrical section 70 is added. This
additional section provides the benefit of shortening the length
between the end of the section 70 at the solids hub 40. This
reduces the length of travel that the conical portion of the screw
conveyor must transport solids which have been removed from the
solids laden inlet feed.
[0023] The modification of the structure of FIG. 1 to that of FIG.
2 provides an additional advantage. The length of the decanting
centrifuge between the point at which the inlet feed enters the
region between the screw conveyor and the interior surface of the
outer body is known as the "clarification length." The centrifuge
10 of FIG. 1 does not have a well defined clarification length
because the inlet feed enters the subject region all along the
inlet plenum 44. At best, the clarification length is roughly the
length of the cylindrical portion of the centrifuge. In contrast,
the centrifuge 50 provides an additional length of cylindrical
section, thereby making the clarification length longer, and
improving the effectiveness of the centrifuge in removing solids
from the inlet feed.
[0024] Thus, the method of the present invention comprises
disassembling the centrifuge illustrated in FIG. 1 as if to perform
an overhaul. The overhaul would routinely include such matters and
replacing bearings, wear inserts, and the like which suffer
accelerated wear during routine use of the centrifuge. Once the
centrifuge is apart, the bowl section of the outer body is extended
by installing the bowl section 54. The screw conveyor 20 is removed
and replaced with the screw conveyor 58, defining a longer
cylindrical portion and having outlet nozzles adapted to impart
rotational movement to the inlet feed. Then, a new, higher angle
slope conical section 56 is installed.
[0025] The principles, preferred embodiment, and mode of operation
of the present invention have been described in the foregoing
specification. This invention is not to be construed as limited to
the particular forms disclosed, since these are regarded as
illustrative rather than restrictive. Moreover, variations and
changes may be made by those skilled in the art without departing
from the spirit of the invention.
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